Slurry explosive compositions have been known heretofore and are disclosed, for example, in U.S. Pat. Nos. 2,992,912; 3,091,559; 3,094,443; 3,287,189; and 3,475,238. These compositions are of the general type which comprises a particulate solid phase and a separate liquid phase intimately mixed with the solid phase. The liquid phase includes a thickening agent such as a synthetic or natural gum which is hydrated and gelled so as to maintain a desired, even distribution of the particulate solid phase throughout the liquid phase and also to provide the explosive composition with resistance to connate water in the bore hole. As suggested in the aforementioned U.S. Pat. No. 3,475,238 and in U.S. Pat. No. 3,737,350, prior art compositions are formulated such that, when the liquid phase is initially prepared, gelling or cross-linking tends to occur shortly thereafter, usually within a few days, so that subsequent mixing with the particulate solid phase is difficult, time consuming and requires sophisticated mixing equipment. Thus, in U.S. Pat. No. 3,475,238, it was taught that the gelling or cross-linking process could be extended from a few days up to about thirty days or more; and even if cross-linking had taken place, the gel could be broken down by the addition of sufficient acid to adjust the pH to an acidic range. This procedure allowed more time in which to accomplish mixing of the liquid phase with the particulate solid phase. After such mixing, the material could be relatively rapidly gelled by the addition of a cross-linking agent.
In U.S. Pat. Nos. 3,094,443 and 3,091,559, compositions are presented in which the liquid phase contains substantial amounts of either aqueous ammoniacal solutions or anhydrous liquid ammonia. These latter materials require that mixing be accomplished at a facility which is equipped to store and process volatile compounds. Thus, in U.S. Pat. No. 3,091,559 it was taught that the explosive composition be poured into polyethylene plastic bags which were ultimately transported to the detonation site. Similarly, in U.S. Pat. No. 3,094,443 the explosive compositions were thickened or gelled in order to reduce the loss of ammonia vapor and render the composition less noxious in handling.
Gelling or cross-linking of the explosive composition at a mixing plant, as suggested in the aforementioned patents, renders the use of the composition difficult if not impossible to use where it is desirable to retain the option of deactivating the explosive composition by flushing out the soluble components with an excess of water. In contrast to the prior art, the present invention contemplates a novel pre-mix liquid phase composition and method of preparing a slurry explosive which are eminently suitable for mining and other industrial uses as well as for certain military applications where transportation and storage of materials are of special significance. The present compositions are also highly useful where it is desired to have the capability of storing slurry explosive composition materials safely and without fear of explosion and for long periods of time, on the order of months or even years, prior to ultimate use. Furthermore, it is desired that the slurry explosive composition be such that ingredients can be easily and quickly mixed at the site of intended use without the need for sophisticated mixing equipment.
It is an object of the present invention to provide a novel method for preparing a slurry explosive whereby the sophisticated elements and complex agitation thereof are incorporated in a pre-mixed liquid phase so that sufficient particulate material can be added to produce a finished explosive product by simple on-site mixing.
It is another object of the invention to provide a detonation insensitive liquid pre-mix capable of being safely stored for periods of at least a year without gelling or cross-linking and adapted ultimately to be mixed with particulate fuels and oxidizers to produce a slurry explosive.
An additional object of the invention is to provide a novel pre-mix composition whereby a slurry explosive which produces a detonation of usable magnitude and force may be mixed from stable components at the point of use without the need for complex mixing techniques.
A still further object of the invention is to provide an easily mixed slurry explosive composition which is highly viscous yet displays no cross-linking so that it may be easily rendered inactive by the addition of an excess of water, or may be catalytically cross-linked at the point of use to allow its use in bore holes containing connate water.
Other objects and advantages of the invention will become apparent to one skilled in the art upon becoming familiar with the following description and claims.